1. Technical Field
The present invention relates to an image processing apparatus, an image processing method, and a computer readable-medium.
2. Related Art
In the field of image processing, a technology has been known which detects a specific region as a region of interest (ROI) from an image to be processed by generating a plurality of feature maps representing physical features obtained from the image and integrating them.
As a more concrete method, for example, according to Treisman's feature integration theory, a plurality of feature maps are integrated to obtain a saliency map. According to the theory of Itti, Koch et al., feature maps are each normalized by the square error from the average value of each, and all the feature maps are integrated by the linear combination method. Then, the integrated feature map is recursively filtered by a difference-of-Gaussian filter, and a local peak of the finally obtained filtering result is extracted as a region of interest (see, for example, Non-patent Reference 1).
For the plurality of feature maps used by the above-mentioned theories, it is considered typical to use the nature of paying attention with higher priority to a visually salient object in the initial stage of the human viewing process such as high lightness, a specific color or high contrast.
[Non-patent Reference 1] Laurent Itti, Christof Koch, and Ernst Neibur, “A Model of Saliency-Based Visual Attention for Rapid Scene Analysis”, IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE, (U.S.A.), IEEE Computer Society, November 1998, Vol. 20, Number 11, pp. 1254-1259
However, although the region of interest (ROI) detection methods based on the above-mentioned theories are considered effective at detecting the feature of each individual image region in an image to be processed, the methods do not consider detecting the feature of each individual image region in consideration of information that the image to be processed, as a whole, has (for example, a composition).